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<H1>?C1 #=> ?C2</H1>
The constraint expression C1 implies the constraint expression C2.


<DL>
<DT><EM>?C1</EM></DT>
<DD>An arithmetic constraint expression.
</DD>
<DT><EM>?C2</EM></DT>
<DD>An arithmetic constraint expression.
</DD>
</DL>
<H2>Description</H2>
   This constraint states that the constraint expression C1 implies the
   constraint expression C2.  If this is already the case, it simply
   succeeds.  Otherwise it is suspended and after each domain change that
   may cause C1 to succeed, it is woken and re-evaluated.  If C1 is true,
   C2 is imposed as a constraint.

<P>

<H3>Fail Conditions</H3>
   Fails if C1 is true and C2 is false.


<H3>Resatisfiable</H3>
   No.
<H2>See Also</H2>
<A HREF="../../lib/fd/HRF-2.html">#\/ / 2</A>, <A HREF="../../lib/fd/HFR-2.html">#/\ / 2</A>, <A HREF="../../lib/fd/HLEG-2.html">#<=> / 2</A>, <A HREF="../../lib/fd/HRP-1.html">#\+ / 1</A>
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